1. Field of the Invention
The present invention relates to a sensing device and a display method in the sensing device.
2. Description of the Prior Art
A sensing device such as a photoelectric sensor, a proximity sensor and the like detects an external physical state and compares feature quantity representing physical state with a set threshold value to output an on-signal or a off-signal in dependence upon the comparison result. In such a sensing device, an output indicator lamp is turned on or off in accordance with the output state in order to indicate the output state (on or off state). Further a level of the feature quantity is displayed on a bar graph display device comprising a plurality of indicator elements in order that the level of the feature quantity is recognized. For example, as shown in FIG. 14a, the feature quantity is displayed in a form of a bar graph using a plurality of indicator elements 90, and the output state is displayed by an output indicator lamp 91. Alternatively, as shown in FIG. 14b, the feature quantity is digitally displayed on a numerical display device 92, and the output state is displayed by an output indicator lamp 93.
However, in accordance with the display method in the conventional sensing device, although the output state and the feature quantity are confirmed, the relation is not realized between the displayed feature quantity and the set threshold value. Since it cannot be judged whether the threshold value is appropriate, difficulties arise in setting a threshold value so that the sensing device operates under optimum conditions. Even in a sensing device in which a threshold value can be finely adjusted, adjusting the threshold value to an optimum value is impossible, as the relation is not clear between the displayed feature quantity and the set threshold.